1. Field of the Invention
The present invention relates to an air bag case assembly, and more particularly to an air bag case assembly comprising a track mounted to an air bag case, and a rail mounted to the hub of a steering wheel and configured to allow the track to engage therein.
2. Description of the Related Art
Generally, an air bag system for a vehicle is mounted to a steering wheel for protecting a driver from shock when a collision of the vehicle occurs. Furthermore, the air bag system is mounted to the steering wheel in a vertically movable manner, thereby further functioning to turn on/off a horn switch mounted to the steering wheel.
Referring to FIG. 1 illustrating a conventional air bag system, it comprises an air bag case mounted to a hub 2 provided in a steering wheel 1, an inflator 14 for ejecting high pressure gas as soon as a collision of the vehicle is detected by an impact sensor, and an air bag 16 accommodated in the air bag case so as to be instantly expanded toward a driver by means of the high pressure gas ejected from the inflator 14.
The air bag case comprises an air bag cover 10 for covering the open upper surface of the hub 2 of the steering wheel 1, a retainer 11 laid on the hub 2 of the steering wheel 1 for supporting the inflator 14 and air bag 16, a rib 12 protruding downwardly from the air bag cover 10 so as to surround the retainer 11 and be fastened to the retainer 11 by means of rivets 20, and a bracket 13 fastened at one side thereof to both the rib 12 and retainer 11 by means of the rivets 20 and fastened at the other side thereof to one side surface of the hub 2 of the steering wheel 1 by means of bolts 22.
The air bag cover 10 is formed with a tear line 17 at a region 10A located inside the rib 12 so that the air bag cover 10 is easily and smoothly broken along the tear line 17 during the expansion of the air bag 16.
Now, the operation of the conventional air bag system configured as stated above will be explained.
When a collision of the vehicle is detected by means of the impact sensor, the high pressure gas is ejected from the inflator 14 into the air bag 16. As the air bag 16 is expanded by means of the high pressure gas filled therein, it causes the cutting of the air bag cover 10 along the tear line 17, thereby being expanded toward the driver.
In such a conventional air bag system, however, since the air bag case is assembled to the steering wheel 1 as the bracket 13 is fastened together with both the rib 12 and retainer 11 by means of the rivets 20, and further fastened to the hub 2 of the steering wheel 1 by means of the bolts 22, there exist several problems in that the number of assembly elements is large, separate tools for fastening the rivets 20 and bolts 22 are required, such a fastening work is performed within a relatively narrow space, and an operator has to bend his/her back in order to perform the fastening. For these reasons, assembly cost and time of the air bag case are disadvantageously increased.
Furthermore, since the bolts are liable to be worn at their screw threads during the screw fastening thereof, the bolt 22 should be repeatedly fastened several times.